ENSO situation summary
ENSO-neutral is currently in place in the tropical Pacific, but there are good indications that El Niño will form later this year, and it may potentially be a strong El Niño. There is about an 85% chance for ENSO-neutral to continue through April-June, with a 60% chance that El Niño will form during May-July.
As of 15 March 2026, the 30-day NINO3.4 Index (in the central equatorial Pacific) was -0.08˚C, in the neutral range. The 30-day relative Niño 3.4 Index (RONI) was -0.56˚C, on the La Niña side of the neutral range and reflective of the central equatorial Pacific being cooler than the average of the global tropics.
The Southern Oscillation Index (SOI) was on the La Niña side of the neutral range during December 2025 – February 2026 (+0.5), while the February value was +1.0 (i.e. just reaching the La Niña threshold).
Subsurface ocean temperatures in the equatorial Pacific are now above average or well above average nearly everywhere except for some shallow cool anomalies in the central Pacific.
Cooler than average temperatures are currently located in the central equatorial Pacific to depths of about 50 metres. However, elsewhere across the equatorial Pacific, warmer than average temperatures are observed at the surface and subsurface. Very warm water located at depths of 50-200 metres indicates a likely trend toward El Niño later this year.
During April-June, model guidance favours a continued chance of above normal rainfall across Micronesia, with rainfall chances also increasing along the equator. This may lead to enhanced rainfall for island groups such as Palau, Guam, the Northern Marianas, Federated States of Micronesia, the Marshall Islands, Nauru, and much of Kiribati.
Conversely, drier than normal or much drier than normal conditions are likely to occur for many island groups just south of the equator, particularly from Tuvalu east to northern French Polynesia (see pages 6-7 for more information).
Tropical cyclone season in the southwest Pacific continues through the end of April 2026.